You must first remove the mother board.

Then you must remove any PCI cards you have installed.

We will be dealing with #4 which is the stock heat sink for the CPU. The 6500 has a small fan inserted in the heatsink. Unfortunately I do not have a 6500 but Torsten was kind enough to send me pictures of his experience at installing a new CPU fan. Thanks Torsten!

This picture is just to show you that you must remove any PCI cards installed since the fan is directly underneath them.

The image below shows Torsten's 6500 with the fan in place on the heatsink.

You need to remove the two screws (show with the red arrows) on opposite sides of the fan.

Then you can just lift the fan right off the heatsink and unplug the power cable that is attached to the mother board.

At this point, you can install the new fan in the reverse order. Click here for info on obtaining a new CPU fan. You will have to scroll down some to get to the CPU fan section. The info on the fan Torsten used can be found on that page as well.

Here are some extra pictures Torsten sent me that I thought might be helpful. The first two show the stock CPU fan next to a ruler so you can get the measurements of it.

These next four pictures show the stock fan in comparison to the new fan Torsten bought. Below is the stock 6500 CPU fan.

Below is the aftermarket fan Torsten bought.

Below is a comparison of the two. Notice how much longer the power cable is for the replacement fan. You can either cut the wire to make it shorter or wrap it up to keep it out of the way.

Below is a comparison of the power plugs. Even though the connector for the replacement fan is larger (white plug), it still has the positive and negative pin outs in the correct locations and connects fine.

These next two pictures show the heatsink clip and the mother board without the heatsink installed. To remove the heatsink you just need to unclip the heatsink in the 4 locations shown (red arrows) from under the mother board.

When reinstalling the heatsink you must make sure to apply heatsink compound (available at Radio Shack or any good electronics store) to get better heat transfer from the CPU to the heatsink. The center of the CPU (red arrow) is the only part that actually touches the heatsink so there is no need to goop the compound all over the place! In fact that could be bad as the compound can conduct electricity so make sure it doesn't touch any electrical components!